如何获得TreeView的返回值，即子节点node.Name的值

DataTable dtGroupName = Cheeli.DBUtility.DbHelperSQL.GetDataTable("select distinct GroupName from SysRes"); foreach (DataRow rows in dtGroupName.Rows)
{
string GroupName = rows["GroupName"].ToString();
TreeNode root = new TreeNode(GroupName);
tvPermissions.Nodes.Add(root);
SqlParameter[] parameters = { new SqlParameter("@GroupNameText", root.Text) };
string sql = "select * from SysRes where GroupName=@GroupNameText";

DataTable dt = Cheeli.DBUtility.DbHelperSQL.GetDataTable(sql, parameters); foreach (DataRow row in dt.Rows)
{
string PromiseName = row["PromiseName"].ToString();
TreeNode node = new TreeNode(PromiseName);
node.Name = row["Id"].ToString();
root.Nodes.Add(node);
}
}

private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
{
textbox.Text=treeView1.SelectedNode.Text;//获取节点值赋给textbox
}

this.treeview1.afterselect += new system.windows.forms.treevieweventhandler(this.treeview1_afterselect);//点击节点事件

private void treeview1_afterselect(object sender, treevieweventargs e)     {     textbox.text=treeview1.selectednode.text;//获取节点值赋给textbox

    }